Boosting Testosterone & Understanding Your Testosterone Levels (Aging, Muscle Growth & Nutrition)

Episode Overview

• Human Performance Scientist Dr. Andy Galpin (who notes he is not an MD, does not prescribe testosterone, and has sponsor ties to Momentous, David protein bars, and LMNT electrolytes) breaks down the true relationship between testosterone, aging, metabolic health, caloric intake, and muscle growth.
• Challenging the conventional wisdom that testosterone inevitably declines by 1% per year after age 40, recent meta-analyses show that age-related drops are actually driven by obesity and metabolic dysfunction rather than chronological aging itself.
• Caloric intake and testosterone follow an inverted-U curve: losing weight via a caloric deficit substantially boosts testosterone in overweight or obese individuals, whereas extreme under-eating and Relative Energy Deficiency in Sport (RED-S) cause severe, albeit reversible, hormone crashes in lean athletes.
• Clinical standards—including new Defense Health Agency (DHA) guidelines—emphasize that diagnosing low testosterone requires multiple properly timed blood draws, evaluation of binding proteins like SHBG, and the presence of actual clinical symptoms before considering Testosterone Replacement Therapy (TRT).
• Within the normal physiological ("eugonadal") range of 300 to 1,100 ng/dL, baseline testosterone levels, acute post-workout hormone spikes, and muscle androgen receptor density do not predict how much muscle an individual will build from resistance training.

Key Concepts

• Prevalence of Low Testosterone vs. True Clinical Deficiency: While 25% to 30% of adult men have clinically low total testosterone (defined as <300 ng/dL), this is heavily skewed by body composition: roughly 40% of clinically obese men have low testosterone, compared to less than 10% of non-obese men. Furthermore, when combining lab values (<300 ng/dL) with actual clinical symptoms (e.g., low libido, poor energy), prevalence drops from 25% to sub-5% (and in some cases <1%). Causality data indicates that obesity causes low testosterone, not the reverse.
• The Inverted-U Curve of Caloric Intake and RED-S: In individuals with >25% body fat or a BMI >30, caloric restriction (via diet, bariatric surgery, or GLP-1s) causes testosterone to rise substantially. At ~20% body fat, testosterone holds steady during moderate deficits. However, in lean individuals, aggressive deficits cause endocrine suppression: 15% to 25% of elite athletes exhibit clinically or subclinically low testosterone due to RED-S or exercise hypogonadal male condition. In women, normal intake is ~30 kcal/kg of fat-free mass per day; dropping to 15 or sub-10 kcal/kg (e.g., dropping from 2,500 to 1,000 kcal/day) causes severe endocrine crashes. Dr. Galpin notes his non-evidence-based intuition is that men can tolerate a lower threshold (~20 to 25 kcal/kg of fat-free mass) before crashing.
• Extreme Leanness vs. Extreme Deficits: Based on n=1 peer-reviewed case studies of physique competitors, extreme dieting drops total testosterone by 20% to 80% (e.g., from 400–600 ng/dL down to 50 ng/dL, or 900 ng/dL down to 200 ng/dL), especially below ~5% body fat. However, the severity of the caloric deficit matters more than body fat percentage alone: Dr. Galpin has observed 170 to 200+ lb clients eating 1,000 kcal/day drop to sub-50 ng/dL despite having 15%–18% body fat, whereas hundreds of his clients maintain normal levels (400–800 ng/dL) at sub-8% body fat by dieting slowly. While long-term decade-spanning studies are lacking, short-term and military studies show diet-induced low testosterone rebounds within days, weeks, or months upon refeeding to maintenance or 10%–20% above.
• Metabolic Health Abolishes Age-Related Testosterone Decline: A meta-analysis by Dr. Ben House evaluated 5 metabolic health criteria: (1) Blood pressure <120/80 mmHg, (2) Fasting glucose <100 mg/dL or HbA1c <5.5%, (3) Total triglycerides <150 mg/dL, (4) HDL cholesterol >40 mg/dL, and (5) Waist-to-hip ratio <0.5. Obesity (waist-to-hip ratio) is the primary driver, increasing low testosterone risk 2 to 3.5 times (or 7.5-fold when comparing obese to normal-weight individuals), while blood pressure is the least impactful. Each additional risk factor increases low testosterone likelihood by ~71%. Meeting 5/5 criteria carries a <1% risk of low testosterone; 4/5 carries <5% risk; 3/5 carries ~20% risk; and 0/5 carries a 20x greater risk than 5/5, representing a 200 to 250+ ng/dL difference in total testosterone. When controlling for body composition and metabolic health, the traditional 1% per year (10%–12% per decade) age-related decline disappears entirely; Dr. House's dataset actually showed an increase of ~8 ng/dL per decade of aging (though Dr. Galpin hedges that more database access is needed to confirm if this slight increase is a real phenomenon).
• Lifestyle Stacking vs. Minor Suppressors: Secondary factors like lipid-lowering medications, marriage, or having children typically lower testosterone by 10 to 40 points on average (e.g., lipid-lowering meds average a 20 to 30 point drop, though wide individual standard deviations can reach 200 points). Stacking 3 to 5 of these minor constraints can cause a 150 to 200 point drop, which is why removing constraints via lifestyle stacking routinely rebounds clients' testosterone by 200 to 300 ng/dL.
• Diurnal Rhythm, Free Testosterone, and the SHBG "Math Problem": Testosterone follows a diurnal rhythm, peaking at night and dropping by 150 to 250 points throughout the day (e.g., a 7:00 AM vs. 10:00 AM test can differ by 100+ points). Dr. Galpin shares a hunch, based on initial evidence in men 55 and older, that a flattened diurnal wave amplitude may drive age-related symptoms more than total numbers. In the blood, 97% to 99% of testosterone is bound (tightly to SHBG or loosely to albumin), leaving only 1% to 2% unbound ("free"), while "bioavailable" testosterone (free plus albumin-bound) makes up 35% to 45%. Standard male SHBG lab ranges are ~15 to 55 nmol/L (up to 75 nmol/L over age 50), and 25 to 125 nmol/L for premenopausal women (17 to ~130 nmol/L postmenopausal), though fit individuals routinely test at or above the high threshold. Because SHBG naturally rises with age (~5 to 8 nmol/L per decade) but drops with poor metabolic health (~10 points between a 5/5 and 0/5 metabolic score at age 50), an unhealthy 60-year-old's age-related rise and disease-related drop cancel each other out, placing them in the "normal" reference range and masking their metabolic pathology.
• TRT Outcomes and Risks: While TRT consistently improves libido/sexual function (in clinically low individuals), body composition, bone density, and some mental health markers, evidence is weak for improvements in energy, vitality, and cognition. Furthermore, if TRT pushes hematocrit north of 52% to 54%, it creates a severe risk of acute cardiovascular events or death ("ketchup in the blood").
• Testosterone and Hypertrophy: Within the eugonadal range (300 to 1,100 ng/dL), neither baseline endogenous hormones (total/free T, SHBG, IGF-1, insulin) nor muscle cell androgen receptor density/sensitivity (per Dr. Mike Roberts' lab) explain why some individuals gain more muscle than others on identical programs (though Dr. Galpin caveats that more data is needed in 55-to-80-year-olds). Acute post-lifting testosterone bumps of 25 to 50 ng/dL last only minutes and do not impact hypertrophy. Even when testosterone is pharmacologically suppressed 10- to 20-fold (e.g., from 500 down to 50 ng/dL), men still build muscle over 8 to 10 weeks of lifting, though gains are blunted (gaining ~0.5 kg vs. 1–2 kg, or 2 lbs vs. 4 lbs over 3 months). Conversely, supraphysiological exogenous testosterone builds muscle without lifting, and combining it with lifting over 8 to 12 weeks yields an extra 1 to 2 kg of muscle and 1 kg of fat loss.
• Anabolic Resistance and Protein Contribution: Aging (exacerbated by obesity, insulin resistance, and inflammation) causes "anabolic resistance," where a given dose of protein (e.g., 25g) stimulates less muscle protein synthesis at age 80 than at age 30. However, resistance training provides 90% to 95% of the stimulus for muscle growth, while protein intake accounts for only ~5%.

Quotes

• At 0:01:31 - "First and foremost is he made a really compelling argument that according to the analysis and studies that he's published in the last few months, there doesn't seem to be a drop in testosterone with aging." - introducing Dr. Ben House's research showing that metabolic dysfunction, rather than chronological age, drives declining testosterone.
• At 0:02:21 - "In that things like your total testosterone is not what's going to predict how well you respond to strength training, as long as you are within what's called eugonadal range, meaning your total testosterone level is normal." - explaining that normal physiological variations between 300 and 1,100 ng/dL do not dictate muscle growth potential.
• At 0:07:54 - "Meaning as long as your waist circumference or body mass index, your BMI, does not clinically diagnose you as obese or higher, there's a 90% chance your testosterone's not clinically low." - highlighting how rare clinically low testosterone (<300 ng/dL) is among non-obese men.
• At 0:08:22 - "The causality looks to be almost always the reverse, where the obesity causes the low testosterone, not the inverse." - clarifying the directional relationship between excess body fat and endocrine suppression.
• At 0:10:50 - "And you say, well, how many people have low testosterone as well as have clinical symptoms of low testosterone? And that number falls from 25% of men to sub 5%." - illustrating the massive gap between isolated lab numbers and true symptomatic hypogonadism.
• At 0:23:50 - "And so I don't think we have enough evidence at this point to suggest that dieting, even extreme, will permanently crush your testosterone forever." - noting that while multi-decade studies are lacking, short-term data shows caloric-restriction-induced low testosterone rebounds upon refeeding.
• At 0:33:46 - "Those folks who are classified as obese alone had about a seven and a half fold risk of low testosterone relative to people who are normal weight." - quantifying the impact of obesity as the single largest metabolic driver of low testosterone.
• At 0:35:05 - "This is then to say somebody who is 70 years old, seven zero, and has all five perfect criteria, would have on average somewhere between a 70 to 100 points higher testosterone than somebody in their 40s that has one of these molecular signatures." - demonstrating that a metabolically healthy older adult outperforms a metabolically unhealthy middle-aged adult in testosterone production.
• At 0:38:50 - "All then to say, at equal cardiometabolic health status, older men are going to have as much, if not maybe even slightly more testosterone than younger men." - summarizing the meta-analysis findings when controlling for body composition and metabolic biomarkers.
• At 0:47:06 - "I cannot be more clear here: you really, really, really should avoid taking hormone replacement therapy or testosterone replacement therapy or any medication or even peptide relating to testosterone production based upon a single blood draw." - warning against premature medical intervention due to high daily and situational variability in hormone testing.
• At 0:48:13 - "A diagnosis of low testosterone requires at minimum of two morning fasted lab tests." - citing the new Defense Health Agency clinical practice guidelines co-developed by Dr. Gabrielle Lyon.
• At 0:48:50 - "In these guidelines, they explicitly state that neither of these tests should be done within 30 days of extreme physical training, sleep deprivation, or acute illness." - explaining the strict pre-testing conditions required to avoid false-positive low testosterone readings.
• At 1:10:41 - "You get this math problem to where you are 60 years old, you're not in great metabolic health, but it elevated with your age, it dropped with your poor metabolic health, and so you end up being smack dead perfect in the reference range." - explaining how opposing age and disease effects on SHBG can mask metabolic pathology on standard lab panels.
• At 1:16:00 - "All that then to say, I don't think there's any strong evidence to make your exercise programming choices or nutrition choices based upon which one will give you a short, acute rise or bump or boost in testosterone." - dismissing the practice of designing workouts around transient 25 to 50 ng/dL post-exercise hormone spikes.
• At 1:16:21 - "If you are below 300 in total testosterone, you are going to constrain your ability to grow muscle, but you will not eliminate it." - referencing pharmacological suppression studies showing men still gain ~0.5 kg of muscle over 8 to 10 weeks even at castration-level testosterone (~50 ng/dL).
• At 1:36:06 - "Your strength training program doesn't really need to differ as you age." - concluding that exercise selection, intensity, volume, and range of motion remain fundamentally identical for 30-year-olds and 80-year-olds.

Takeaways

• Target the 5 Metabolic Health Markers to Naturally Boost Testosterone: Before blaming age or seeking hormone therapy, optimize your metabolic health to naturally rebound testosterone by 200 to 300 ng/dL: keep blood pressure <120/80 mmHg, fasting glucose <100 mg/dL (or HbA1c <5.5%), total triglycerides <150 mg/dL, HDL cholesterol >40 mg/dL, and waist-to-hip ratio <0.5. Achieving just 3 or 4 of these reduces your risk of clinically low testosterone to ~20% or <5%, respectively.
• Use Modest Caloric Deficits When Lean: If you are overweight or obese (>25% body fat or BMI >30), utilize a caloric deficit to lose fat and substantially increase your testosterone. However, if you are already lean, avoid extreme diets (e.g., 1,000 kcal/day or <15 kcal/kg of fat-free mass); instead, use a slow, modest deficit of 200 to 500 kcal/day to preserve endocrine function while getting lean.
• Refeed to Reverse Diet-Induced Suppression: If you have suppressed your testosterone through extreme dieting or high-volume athletics (RED-S), bring your caloric intake back to maintenance or 10% to 20% above maintenance over several weeks to months to restore normal hormone levels.
• Follow Strict Protocols for Testosterone Blood Draws: Request a baseline total testosterone screen at age 30 (or earlier if desired). Never act on a single blood test; always confirm with at least two fasted, early-morning blood draws taken at the exact same time of day (as levels drop 100+ points between 7:00 AM and 10:00 AM).
• Eliminate Acute Stressors Before Testing: Ensure all diagnostic blood draws are conducted at least 7 days (per Dr. Galpin's coaching practice minimum) to 30 days (per DHA guidelines) removed from extreme physical training, sleep deprivation, or acute illness to prevent artificial, temporary dips in your lab results.
• Request a Comprehensive Endocrine Panel for Low Readings: If total testosterone tests low across two morning draws, do not immediately jump to TRT. Require a secondary evaluation that includes clinical symptom assessment, SHBG, free testosterone, LH, FSH, prolactin, TSH, T4, ferritin, a complete blood count (CBC), and potentially pituitary imaging to identify the root cause.
• Monitor Hematocrit and Dosage Limits on TRT: If you and your physician initiate TRT, follow DHA guidelines by adjusting your dosage to keep total testosterone between 300 and 600 ng/dL (lowering the dose if it exceeds 600 ng/dL), and closely monitor hemoglobin and hematocrit to ensure hematocrit never exceeds 52% to 54%.
• Consume 1.2 to 2.2 g/kg of Protein Daily: Move past the traditional 0.8 g/kg/day RDA (which only prevents deficiency) and consume at least 1.2 to 1.6 g/kg/day (per updated US federal guidelines) to maintain lean mass and overcome age-related anabolic resistance. Consider aiming for Dr. Galpin's practical target of 2.2 g/kg/day (1 g/lb of body weight) to maximize satiety and improve overall dietary behaviors.
• Train for Mechanical Stimulus, Not Hormone Spikes: Do not select exercises, rest intervals, or nutrition strategies based on whether they produce a brief post-workout testosterone bump. Focus on progressive resistance training, which provides 90% to 95% of the stimulus for muscle growth regardless of whether you are 30 or 80 years old.
• Maintain Foundational Supplementation and Hydration: To support physical and cognitive output during training, avoid even 1% dehydration by replenishing electrolytes (such as 1,000 mg sodium, 200 mg potassium, and 60 mg magnesium in LMNT) and consider taking 7 to 10 grams of high-purity creatine daily (Dr. Galpin's personal protocol using Momentous creatine).